Spark-plug for internal-combustion engines.



E. BAUER.

SPARK PLUG FOR INTERNAL COMBUSTION ENGINES.

APPLIGATION FILED OUT. 26, 1911.

1, 1 27,390. Patented Feb. 9, 1915.

V/TIJESSES lIJ/EIJTUR a g H I 49 2 1 vm aiw UNITED STATES PATENT OFFICE.

Ewen BAUER, 0F STUTTGABT, GERMANY, ASSIGNOB TO THE FIRM 01? ROBERTBOSCH, OF STUTTGABT, GERMANY.

SPARK-PLUG FOB INTEBNALCQMBUSTION ENGINES.

Application filed 0mm: 26, 1911.

T all whom it may concern Be it known that I, EUGEN BAUER, a subject ofthe Emperor of Germany, and residmg at Kornbergstrasse 11", Stuttgart,Germany, have invented certain new and useful Im rovements 'inSpark-Plugs for In ternalombustion Engines; and I do hereby declare thefollowing to be a full, clear, and exact description 0 the invention,such as will enable others skilled in the art to which it appertains tomake and use the same.

This invention relates to spark plugs for internal combustion engines,and more particularly to one of the high tension or jump spark type,which assures satisfactory ignition of the combustible mixturesthroughout a long period of operation without special attention, byproviding such construction and arrangement that one or both of theelectrodes of the plug becomes momentarily incandescent so as to burnaway any residue deposited thereon, but does not remain incandescentlong enough to give rise to ignition at undesired times.

In order to provide satisfactory ignition at all times it is essentialthat no solid or semi-liquid residue resulting from combustion of thecombustible mixtures be allowed to remain on the electrodes, inasmuch assuchresidue would tend to bridge over the spark gap and cause thespark-plug to fail to operate. Itwould be ossible to avoid that defectby so constructmg the electrodes that at least one of them becomesincandescent during the combustion of the gases so that any residuepreviously deposited on the electrode is burned to a non-conducting ash.However, if such procedure is adopted it is necessary to avoid theattendant disadvantage arisin from the circumstance that if the electr eremains incandescent for an extended part of the period between succes-'sive sparks the combustible mixture may be ignited prematurely, forinstance in the compression stroke of the engine.

In accordance with my invention, both of these essential requirementsare simultaneously fulfilled in a satisfactory manner by a constructioninvolving such form and such'material that the heat during eachcombustion period raises the temperature of one or both of theelectrodes of the spark plug sufiiciently high to burn the residuedeposit Specification of Letters Patent.

Patented Feb. 9, 1915.

Serial no. 656,958.

ed thereon to a non-conducting ash; and at the same time the heat isdissipated from the heated part at a rate which quickly lowers thetemperature below the temperature of ignition of the combustiblemixture, whereby the part remains heated above the temperature ofignition for so short a time that premature ignition is impossible.

In the drawings, illustrating several forms of construction inaccordance with my invention, Figure l is a side view and Fig. 2 abottom view of the spark plug showing particularly the form of theincandescent electrode; Fig. 3 is a side View of the lower part of aplug and Fig. 4 a bottom view thereof, wherein the form of theincandescent electrode is modified; Figs. 5 and 6 are similar to Figs. 3and 4 except that the form gfdthe incandescent electrode is again modi-The socket A of the spark plug is provided withathreaded nippleB adaptedto be screwed into the cylinder of the internal combustion engine, andit incloses a body of insulating material C. The insulated electrode Dextends centrally through the insulating body C and is adjustablyfastened therein by the nuts F so that its other end projects centrallyin proximity to one or more electrodes E attached to the inside on thenipple B by soldering, swaging, or otherwise, as is Well known.

In all cases the electrode E, G is made of a metal that strongly resistsfusion, such as nickel or the like, so that it may be heated to atemperature of incandescence without material softening.

In Figs. 1 and 2, I show a plurality of radia ly disposed electrodes Fof wire, havin flattened sparking parts G which exten partly around theinsulated elec trode D but are. separated therefrom by the proper sparkgap. These electrodes are not merely cut off from wire and given acircular edge, but their ends are so formed by flattening them that ateach sparking period the parts G become incandescent and are thereby incondition to burn themselves clean, but that, on the other hand, inconsequence of their large surface and small mass and also inconsequence of the comparativel large mass of the parts E, the heat ofthe sparking parts is so quickly dissipated that they are again cooled,sufliciently to prevent ignition by incandescence,before the followingcompression stroke.

In Figs. 3 and 4, the electrode E, G has a flattened annular part Ginclosing the insulating electrode D and being separated therefrom bythe'proper spark gap as before.

In Figs. 5 and 6, the electrode E, G, has the flattened sparking part Gwith a central hole through which extends the insulated electrode D.

In all of these modifications the parts E, which are massive comparedwith the spark ing parts G, are provided for the purpose of aiding inthe rapid dissipation of the heat from the sparking parts of theelectrodes, as is also the case in the modification shown in Figs. 1 and2.

In each case the electrode E is so formed that the flattened part Gbecomes incandescent at the period of ignition, and during the period ofcombustion the combustion residues deposited are consumed to anonconducting ash so that no bridging over of the spark gap takes place;but because of its large radiating surface and small mass the electrode,in the further course of the explosion period and during the dischargeperiod, is so far cooled that no ignition by incandescence can takeplace at an undesired time.

Having thus described my invention what I claim is 1. In a spark plugfor internal combustion engines, two electrodes separated from eachother by a spark gap, one of said electrodes having a flat sparking partof comparatively small mass so as to become incandescent at the ignitionriod, whereby combustion residues deposited thereon are consumed, andalso havin a comparatively massive part to aid in ssipating the heat ata rate which quickly lowers the temperature of the sparking part belowthe temperature of ignition of the combustible mixture whereby ignitionbv incandescence at an undesired'time is avoided; substantially asdescribed.

2. In a spark plug for internal combustion engines, an electrodeextending centrally through the plug and being insulated therefrom, anda second electrode electrically connected to the plug and separated fromthe other electrode by a spark gap, the second electrode having a fiatsparking part extending in an arc concentric with the first mentionedelectrode, said sparking part having a comparatively small mass so as tobecome incandescent at the ignition period, whereby combustion residuesdeposited thereon are consumed, and the second electrode also having acomparatively massive part to aid in dissipating the heat at a ratewhich quickly lowers the temperature of the sparking part below thetemperature of ignition of the combustible mixture, whereby ignition byincandescence at an undesired time is avoided; substantially asdescribed.

3. In a spark plug for internal combustion engines, an electrodeextending centrally through the plug and being insulated therefrom, anda second electrode entirely surrounding the first mentioned electrodeand being electrically connected to the plug, said second electrodehaving a Hat sparking part of comparatively small mass so as to becomeincandescent at the ignition period, whereby combustion residuesdeposited thereon are consumed, and the second electrode also having acomparatively massive part to aid in dissipating the heat at a ratewhich quickly lowers the temperature of the sparking part below thetemperature of ignition of the combustible mixture, whereby ignition byincandescence at an undesired time is avoided; substantially asdescribed.

In testimony whereof I aflix my 'signature, in presence of twowitnesses.

EUGEN BAUER.

Witnesses REINHOLD ELWERT,

PAUL WOLFART.

It is hereby certified that in Letters Patent No. 1,127,390, grantedFebruary 9, 19l5, upon the application of Eugen Bauer, of Stuttgart,Germany, for an improve ment in Spark-Plugs for Internal-CombustionEngines, an error appears in the printed specification requiringcorrection as follows: Page 1, line 93, for the refer enceletter F readE, G; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patient ()fiice.

Signed and sealed this 11th day of May, A. D,, 1915.

[SEAL] R. F. WHITEHEAD,

Acting Commissioner of Patents.

